What is an ATtiny85?
An ATtiny85 is one of a range of ATtiny microcontrollers. An Arduino Uno is a board that also has a microcontroller on it. The ATmega328 to be exact. It also has a USB input and various other components so you can plug the Arduino Uno straight into a laptop and program and use it.
The Attiny85 is just a small 8-pin chip, in fact, you can get it as an even smaller SMD device. Also, it is an 8-pin DIL so you can’t just program it without some other hardware, however, it is a lot cheaper and smaller than an Arduino Uno. It also uses less power.
Can the ATtiny85 be reprogrammed?
Yes, it can but as it’s an 8-pin DIL microcontroller you’ll need a programmer like the USBasp or alternatively get a developer board with the microcontroller on it.
In my opinion, using a USBasp is a cheaper and easier way to program this microcontroller. Especially if you are a beginner and haven’t got an Arduino Uno.
With a USBasp, you will also be able to program lots of other microcontrollers. You then need to download the free software “Arduino IDE” and the ATtiny support software, also free and then when you’ve set the correct options you are ready to program.
I have a detailed guide on setting Arduino IDE up on Windows and Linux, along with the associated drivers and settings. Click on the link below:
Programming an Attiny85 with a USBasp.
How much memory has an ATtiny85 got?
This device has got two types of memory on board. It has an EEPROM memory of 512 bytes that is non-volatile along with 2096 bytes of flash memory.
What can an ATtiny85 be used for?
Clearly, as a microcontroller, the Attiny85 can be used for lots of applications. Also, it can be used for some of the simpler Arduino Uno projects that don’t use all of its features or all of its inputs and outputs. The ATtiny85 has 5 inputs or outputs furthermore it can stretch to 6 if you program the reset pin to function as an extra in/out.
So if you only need 6 inputs or outputs you may be able to use the device instead of the larger and more expensive Arduino Uno.
You will also find various projects on the internet that use the ATtiny85. There is one such project that I’m currently building which is a MIDI (musical instrument digital interface) to control voltage converter. Amazingly this uses just two chips including the ATtiny85 and a handful of other components.
How to test an ATtiny85
The most straightforward way to test an ATtiny85 is to reprogram it. You can make a simple stripboard project to easily connect an ATtiny85 to a USBasp. Click on the link below if that’s of interest to you:
If you don’t have a USBasp I would get one as it’s probably the cheapest and easiest way to program an ATtiny85 and lots of other microcontrollers.
The instructions are fully detailed showing you every step. You will be installing Arduino IDE software, and USBasp driver software and then running some simple programming steps to verify that you are communicating with the microcontroller, programming and seeing the results of it working.
Pin out diagrams for functions
The ATtiny85 has bidirectional port known as port B. This means it can work as inputs or outputs. These are the PB numbers 0 to 5.
Along with this it also has a 10-bit analogue to digital converter with 4 multiplexed inputs. These are ADC numbers 0 to 3.
An external crystal should be connected between pins 2 and 3 if you need to use one.
Also if you are connecting the ATtiny85 to program via ISP use the pin numbers below.
However, it is by no means essential if you want to play around with an ATtiny85 as you can just use a breadboard. Furthermore, if you want more information about breadboards you can read my article here.
How to program an ATtiny85 without an Arduino?
Last but not least, you should follow my tutorial Programming an ATtiny85 with a USBasp. It contains detailed information but you will need some free downloadable software and a cheap USBasp. By cheap I mean under £10.
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